ECM/PCM question?
Thread Starter
|
New User
Joined: Oct 2007
Posts: 6
Likes: 0
From: LONG ISLAND, NY
ECM/PCM question?
Hello All,
I've got a question, hope this is the right section to ask. My 1995 F350 XL with the 5.8L / 351 V8 runs like new with the exception of the RPM's going nuts. Truck idles normally at 850-900 RPM but during normal street / highway driving RPM's spike to around 3000 RPM. The only way to get it normal is to re-start, but that's only temporary before it happens again. I've tried disconnecting the battery over night, then driving 40-50 miles to reset the computer but the problem returns. Anyone else ever experience this? Possible the ECM/PCM is faulty?
Thanks for any input
I've got a question, hope this is the right section to ask. My 1995 F350 XL with the 5.8L / 351 V8 runs like new with the exception of the RPM's going nuts. Truck idles normally at 850-900 RPM but during normal street / highway driving RPM's spike to around 3000 RPM. The only way to get it normal is to re-start, but that's only temporary before it happens again. I've tried disconnecting the battery over night, then driving 40-50 miles to reset the computer but the problem returns. Anyone else ever experience this? Possible the ECM/PCM is faulty?
Thanks for any input
Postmaster
Joined: Nov 2011
Posts: 3,533
Likes: 17
From: SW Florida
Get the fault codes from the computer (codes can be present even if your check engine light ain't on) and post them back up here.
Your truck is OBD1 so if the computer thinks all is well you should receive a "System OK" code 11 or 111, if you don't get anything at all then we need to start troubleshooting that first.
Your truck is OBD1 so if the computer thinks all is well you should receive a "System OK" code 11 or 111, if you don't get anything at all then we need to start troubleshooting that first.
FTE Legend
Joined: Jun 2006
Posts: 31,930
Likes: 1,499
From: Ottawa, Ontario
Are you saying the actual engine rpms spike while driving down the road in gear?
Or are you saying the tachometer alone spikes but the engine appears to remain at normal rpms while driving along in gear?
Or are you saying the tach and/or engine rpms spike while stopped or in neutral after travelling for some time at speed?
Thread Starter
|
New User
Joined: Oct 2007
Posts: 6
Likes: 0
From: LONG ISLAND, NY
Thanks Dixie and Conanski, Ill try and get those codes to post up here.
To clarify, the engine RPM's will randomly spike while driving in gear as well as when it's in neutral. It's a 5 speed manual. The tach indicates the spikes usually run to 3000-3200 RPM before I shut it down.
To clarify, the engine RPM's will randomly spike while driving in gear as well as when it's in neutral. It's a 5 speed manual. The tach indicates the spikes usually run to 3000-3200 RPM before I shut it down.
Cargo Master
Joined: Mar 2007
Posts: 2,935
Likes: 34
From: Arcadia, Fla
Does the engine it self races up in RPM while in gear? Does it run bad while doing that too?
If it was a automatic tranny, I can see that occuring when a tranny is slipping. But you have a manual tranny, so unless the clutch is wore bone out slipping I'm guessing the tachometer is the problem.
If it was a automatic tranny, I can see that occuring when a tranny is slipping. But you have a manual tranny, so unless the clutch is wore bone out slipping I'm guessing the tachometer is the problem.
Tuned
Joined: May 2007
Posts: 446
Likes: 7
My truck was doing the exact same thing before I pulled the motor. I told myself it was a large vacuum leak, maybe around the intake manifold. The motor has all new gaskets and is almost ready to go back in. If it still has the racing idle, then I will look at the ecm. Mine used to randomly take off. Could be scary depending on where I was.
Trending Topics
Thread Starter
|
New User
Joined: Oct 2007
Posts: 6
Likes: 0
From: LONG ISLAND, NY
For sure an aggravating problem. My 350's been serviced by a friend that owns a dealership here on Long Island. Reason I'm thinking ECM is because just about every other possibility has been ruled out. Never had to replace one, does anyone know if they can be re-flashed/programmed or best just to order a new one?
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
Top 10 Fords at 2026 Carlisle Ford Nationals
Joe Kucinski
3 Best / 3 Worst Parts of Modern Ford Ownership
Brett Foote
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches
Pouria Savadkouei
Every 2026 Ford Engine Explained
Brett Foote
10 Ugly Ford Trucks That We Still Kinda Love
Joe Kucinski
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Fleet Owner
Joined: Oct 2005
Posts: 20,789
Likes: 1,753
From: Kentucky
No, this vintage PCM cannot be re-programmed or flashed...unless you use an aftermarket Tuner like Moates.
There aren't any new ones...they are all remanufactured.
Di you ever pull the codes?
There aren't any new ones...they are all remanufactured.
Di you ever pull the codes?
FTE Legend
Joined: Jun 2006
Posts: 31,930
Likes: 1,499
From: Ottawa, Ontario
Engine reving in gear: Basically there is no way this can just happen unless something is slipping, it's just not possible even if the throttle is stuck wide open. I know you said the clutch isn't the problem but that is the most likely culprit, besides that it could be the rear axle but if that were failing the engine should bounce off the rev limiter not just rev to 3000rpm or so.
A high idle in neutral is a separate problem, could be a vacuum or intake leak but could also be a bad TPS or IAC valve, pull codes for sure and post up what you get(exact code numbers).
Thread
Thread Starter
Forum
Replies
Last Post
discmasher
1987 - 1996 F150 & Larger F-Series Trucks
1
Dec 5, 2006 09:36 AM
wrexpower
1983 - 2012 Ranger & B-Series
1
Jun 7, 2004 06:32 PM